Most switched-mode power supply (SMPS) devices use a full-wave rectifier bridge in the rectifying stage to convert an alternating current (AC) input voltage to a direct current (DC) output voltage. A drawback of the classic four-diode rectifier bridge is the unavoidable forward voltage drop of two diodes when current is flowing. With conventional silicon diodes, this can amount to 1.5 volts or more. The result is wasted power and reduced efficiency. With ideal diode bridge rectifiers using metal-oxide-semiconductor field-effect transistors (MOSFETs), the input voltage cannot exceed the gate-to-source voltage rating of the MOSFETs. This proves undesirable for high voltage applications.
Therefore, there is a need for an improved bridge rectifier design.